On the face of it, there's something extremely appealing about the Caviar House Seafood Bar in Heathrow's Terminal Three. With its marble counter-top and expensive menu, it seems like a little oasis of luxury in an otherwise fairly functional environment. It's certainly a step up from Burger King and McDonald's. What weary traveller, with 10 minutes to spare before his final boarding call, hasn't been tempted to wash down half-a-dozen oysters with a glass of champagne at London's answer to the Brasserie de Terminus?

Unfortunately, appearances can be deceptive. This chain--there's one in every terminal, as well as two at Gatwick, one at Luton and one at Stansted--is a total rip off. You expect to pay less than you normally would when you're in a duty free environment, but at this particular establishment you pay much, much more.

Take the Caviar, for instance. Admittedly, caviar is never cheap, but there's one particular brand on the menu that costs £452 per 100 grams. You can buy cocaine cheaper than that. The 50 grams of Sevruga I ordered as my starter seemed like a bargain in comparison, a snip at £66. In fairness, there was nothing wrong with the accompanying blinis either, though more than six would have been nice. All in all, it was an extremely expensive way to spend two minutes.

I thought my main course--an assortment of sushi for £14.95--might prove better value, but I was wrong. It tasted like it had been made the day before and then kept in a fridge overnight. Didn't anyone ever tell the owners of this chain--a Lebanese family, apparently--that you can't refrigerate sushi rice? The outside of each grain becomes glutinous and soggy, while the inside becomes as hard as uncooked spaghetti.

The fish, too, was revolting. There was a piece of eel that if fired from a catapult would have felled Goliath. The salmon was merely okay and the Tuna had been hanging around for so long it was barely distinguishable from the rice. I think this must rank as the worst sushi I've ever had.

My breakfast, which included a half bottle of champagne, came to £110. What would possess anyone to come back? Yet, surprisingly, the Seafood Bar was doing a thriving trade, with almost every one of its stools occupied by a smartly-dressed young man. What was going on?

The only explanation I can think of is that it taps into the deluded fantasies of solitary male travellers. There's something vaguely seductive about flying by yourself to some foreign climb. No matter how bald and short and fat you are, at some level you think you're James Bond. You imagine you're on your way to an assignation with some exotic heiress called Fatima Lovejoy who's going to tell you about a plot to steal a nuclear warhead.

What better way to perpetuate this illusion than a quick trip to the Seafood Bar? Indeed, the luxury items on its menu are precisely the same ones that Bond himself smuggled into the health farm in his briefcase in Thunderball. The waitress will even provide you with an attractive little carry case so you can take some of these goodies on the plane with you.

It's a pity that the cuisine at the Seafood Bar is so terrible because, in case you hadn't guessed, I'm rather prone to this fantasy myself. Had my meal been even slightly better, I might well have made a return trip. But this was one of those occasions when my imagination ran aground on the shoals of reality. Next time I'm passing through Heathrow, I'm going to pop into Starbucks and have a cappuccino and a toasted sandwich instead. It may not be the breakfast of champions but the total cost is less than 5% of a meal at the Seafood Bar and it tastes at least 500% better.